To prevent the generation of a gap at an interface between a solid electrolyte and an electrode caused by the movement of ion at the inside of the electrolyte, and to cope with the mechanical deformation in a state of keeping the electric bonding of the electrolyte and the electrode.

This invention is made to improve a negative electrode for a lithium secondary battery mounted in a state of being kept into contact with the lithium ion conductive solid electrolyte 13. The negative electrode is composed of a negative electrode collector 21, and a Cs-Rb alloy 26 including metallic lithium 16 and mounted at a solid electrolyte 13 side of the negative electrode collector 21, and a weight ratio of metallic lithium 16 included in the Cs-Rb alloy 26, to the Cs-Rb alloy 26 is Li:Cs-Rb=5:1 through 1:8.